I actually enjoyed Brock's role from the very start till his end! At the end of each series it felt more reassuring knowing that even though we wouldn't see Ash's female travelling companion again we would still have the familiar face in Brock! Even in DP he made me laugh a lot and I'm hesitant to watch BW because too much has changed for me since when I first watched the show as a kid (damn I'm old LOL).
There was so many different story angles they could of worked for him but instead they where lazy and chose not too, personally I felt like he was as much of a foundation of the show as Ash is!!